JDS o2 issues

I recently purchased an o2 off of a seller for about $100~ shipped. He said that the "ac adapter never worked for him" and when it arrived the only way the amp would work is by charging the batteries in a 9v charger. I ordered the triad wau16-400 for some more voltage hoping it would be enough to make sound work on 650's. However whenever I use the "12 volt" or the 16 volt from triad alone with no batteries in it, I have absolutely no sound.. I am essentially saying it will not work with AC adapters that I have bought that no one else seems to have issues with.

Is there something relatively easy to fix with the device, or am I better off trying to fight for a refund if the item is not "perfect" like the seller advertised?

I recently purchased an o2 off of a seller for about $100~ shipped. He said that the "ac adapter never worked for him" and when it arrived the only way the amp would work is by charging the batteries in a 9v charger. I ordered the triad wau16-400 for some more voltage hoping it would be enough to make sound work on 650's. However whenever I use the "12 volt" or the 16 volt from triad alone with no batteries in it, I have absolutely no sound.. I am essentially saying it will not work with AC adapters that I have bought that no one else seems to have issues with.

Is there something relatively easy to fix with the device, or am I better off trying to fight for a refund if the item is not "perfect" like the seller advertised?

I would send a quick e-mail to JDS Labs to try to find out what's really going on. They were very helpful when I bought mine.